The invention pertains to a process for obtaining free fatty acids and/or fatty acid ester, in which, to separate a liquid mixture containing the free fatty acid and/or the fatty acid ester, a rising vapor of the liquid mixture is brought into contact in the column of a distillation apparatus with downcoming condensate formed from the vapor, wherein a mass and/or heat exchange occurs between the vapor and the condensate on internal components of the column.
To implement a process of this type, a short-path distillation, which achieves only a relatively low separation output, is usually conducted because of the considerable sensitivity of the free fatty acids or fatty acid esters to temperature. In this process, a thin film of a liquid mixture, formed on a heated evaporator surface, possibly by wiping, is partially evaporated and sent to a nearby condenser of a short-path distillation apparatus. The geometric arrangement of the evaporator surface relative to the condenser surface and the short path between them makes it possible to use working pressures in the “fine vacuum” range (from 1 mbar to 10−3 mbars) and to work with correspondingly low evaporation temperatures (compare Frank/Kutsche: Die schonende Destillation (Slow Distillation) in the “Verfahrenstechnik” (“Process Technology”) series of Otto Krauskopf Verlag GmbH, Mainz, 1969).
Through use, it is also known that, to conduct the process cited above, a distillation apparatus can be used which comprises a thin-layer evaporator connected to a rectification column and a condenser. Because of the considerable temperature sensitivity of these fatty acid-containing or fatty acid ester-containing liquid mixtures, however, processing them has been considered problematic.